Patent EP-1413622-A1 (EP)
Inventor: GAUTHIER THIERRY
IPC: B01J8/38
Filed: 2003-10-20
Abstract: The catalyst and transport fluid in the tubular zone are at more severe conditions of temperature and/or catalyst to transport fluid mass ratio than those in the annular zone after the charge is injected. The flows from the tubular zone and the annular zone are mixed and then cooled, and the cooled mixture is cracked in the upper part of the reaction zone  The regenerated catalyst is introduced at the bottom of the riser, injecting the charge above the catalyst inlet and injecting (5) the gas to fluidize the catalyst at the base of the riser. The reaction zone has a coaxial internal tubular zone (2) in which part of the regenerated catalyst is circulated using a transport fluid introduced at the bottom end of the tubular zone. The rest of the catalyst and the charge are circulated in an annular zone between the tubular zone and the wall of the riser. The mixture of flows from the tubular zone and the annular zone are cooled by injecting (13) an inert vaporizable fluid at or above the point where the charge is injected.  The ratio of catalyst to charge is between 2 and 10 in the annular zone, preferably between 4 and 7, and between 5 and 20 in the tubular zone, preferably between 8 and 15, with the ratio in the tubular zone greater than that in the annular zone. The temperature in the upper part of the reaction zone is between 500 and 550 degrees C. The density of catalyst in the annular zone below the charge inlet is between 200 and 600 kg/m3 and that in the tubular zone is between 30 and 200 kg/m3. The temperature at the outlet from the reaction zone is controlled by controlling the flow of catalyst and the flow of inert and vaporizable fluid. The temperature at the outlet from the tubular zone is controlled by controlling the flow of transport fluid. The temperature at the outlet from the annular zone is controlled by controlling the flow of catalyst and the flow of inert and vaporizable fluid. The tubular zone has an upper end outlet for the first flow at the same level as or below the level of the charge inlet and at the same level or below the level of the inert fluid injection. A secondary hydrocarbon load which is a light petrol with a final boiling point around 160 degrees C, a heavy petrol, a LCO fraction, an oil fraction with a final boiling point less than 360 degrees C or a petrol containing a majority of long C8- C10 olefins resulting from the oligomerization of C4, C5 or C6 fractions or a mixture thereof. The transport fluid allowing the internal tube to be supplied with catalyst is nitrogen, steam, fuel gas, liquefied petrol gas or a mixture thereof. The surface flow of the catalyst inside the tubular zone is between 0.1 and 10 times, preferably between 0.5 and 3 times, that of the catalyst in the riser. The tubular zone has its lower end below the level of the charge injection. The tubular zone contains at least one restriction or valve at its lower end allowing a pressure drop to be created to facilitate control of the catalyst flow into the tubular zone. The section of the tubular zone is between 0.1 and 0.5, preferably between 0.15 and 0.30 times that of the riser. The lower part of the riser containing the tubular and annular zones is at least partially conical, with the base of the cone near the upper end of the tubular zone. The upper end of the tubular zone is above the level of injection of the charge and below the level of injection of the inert fluid.